Granular Formulations Research Articles

Evaluation of Experimental Extended-Delivery Granular Preemergent Herbicide Formulations for Direct Application to Nursery Containers

Abstract Studies evaluated the efficacy of experimental extended-delivery herbicide formulations for direct application to containers. The purpose for direct application to containers is to reduce non-target loss from the current practice of broadcast applications. A separate laboratory study was also conducted to evaluate the rate response of oryzalin on germination of large crabgrass (Digitaria sanguinalis L.). Results of the laboratory study indicate that crabgrass germination is reduced when seeds are exposed to the preemergence herbicide oryzalin at concentrations of ≥0.025 parts per million. Experimental herbicides were produced by formulating polymeric exchange resins and cellulose complex carriers with oryzalin. Experimental herbicides reduced weed shoot dry weight at 120 DAT and 150 DAT when compared to Rout®, Surflan® and the untreated control.

Granular Pesta formulation of Fusarium oxysporum f. sp. orthoceras for biological control of sunflower broomrape: efficacy and shelf-life

Formulation of fungal propagules encapsulated in a wheat-gluten matrix (termed ‘Pesta’) has proved to be a suitable technique for the development of Fusarium oxysporum f. sp. orthoceras (FOO) as a bioherbicide for sunflower broomrape ( Orobanche cumana ). To improve the efficacy of this fungus, 19 Pesta formulations, using two types of fungal spores and 8 adjuvants, used singly or in combinations, were examined for their shelf-life and for efficacy under greenhouse conditions. Amending Pesta with yeast extract reduced the loss of viability of microconidia and chlamydospores during production of the formulations by 40 and 100%, respectively. Sodium alginate and Water Lock also prevented loss of viability of chlamydospores during Pesta production. The longest shelf-life (inoculum viability) was obtained when granules were stored at 3 °C. In greenhouse experiments, there were no differences among the 19 Pesta treatments in disease severity (DS). In terms of the number of Orobanche attachments, Orobanche dry matter, and the number of Orobanche shoots that produced seeds, the most effective formulations were Pesta 14 (containing chlamydospores [PC] with yeast extract, glycerol, and sucrose as additives), Pesta 1 (containing microconidia [PM] with yeast extract and sucrose), Pesta 5 (PM with yeast extract, glycerol, and sucrose), Pesta 7 (PM with sodium alginate as an additive), and Pesta 15 (PC with stillage). These formulations produced 99, 98, 98, 97, and 97%, DS, respectively, and caused reduction in Orobanche biomass by 80, 76, 71, 80, and 67%, respectively. These Pesta formulations of FOO increased sunflower seed yield by 5–11 times in comparison with the negative control inoculated with fungus-free Pesta. In general, applications of the formulations of FOO in Pesta did not affect the number of leaves, stem diameter, plant height, or the dry matter of roots of sunflower or the rate of photosynthesis in sunflower plants.

Controlling Liverwort and Moss Now and in the Future

The liverwort, marchantia (Marchantia polymorpha), and silver thread moss (Bryum argenteum) are two highly invasive and difficult to control pests in containerized ornamentals. Container trials were conducted evaluating marchantia and silve r thread moss control with preemergence and postemergence applications of chlorothalonil, captan, ammonium chlorides, hydrogen dioxide, flumioxazin, oxyfluorfen, pelargonic acid, acetic acid (vinegar), copper sulfate, cinnamaldehyde, prodiamine, and oxadiazon. Flumioxazin, oxyfluorfen, pelargonic acid, acetic acid, and oxadiazon provided acceptable preemergence and/or postemergence marchantia and silver thread moss control; however, no product provided acceptable control of these weeds at all evaluations. Under controlled environmental conditions marchantia and silver thread moss were controlled with flumioxazin, oxyfluorfen, pelargonic acid, acetic acid, and oxadiazon. In addition to providing postemergence control of these weeds, flumioxazin, oxyfluorfen, and oxidiazon also had residual activity when applied to potting media. However, the length and effectiveness of the preemergence control with flumioxazin, oxyfluorfen, and oxadiazon was dependant upon formulation. In a separate study comparing granular and sprayable formulations of flumioxazin, oxyfluorfen, and oxidiazon, results indicated control of established marchantia and silver thread moss was greater with sprayable formulations when compared with granular formulations. Similarly, sprayable formulations of these active ingredients enhanced residual marchantia and silver thread moss control. The granular and sprayable formulations of flumioxazin provided greater preemergence and postemergence control of marchantia and silver thread moss when compared with granular or sprayable formulations of oxyfluorfen and oxadiazon, and of the products evaluated, displayed the greatest level of activity against these weeds.

Herbicide Losses in Runoff of Containerized Plant Production Nurseries

Herbicide use in containerized plant production nurseries is a vital tool for weed management and the production of plants desired by the consumer. Clemson University researchers have conducted studies aimed at determining the amount of herbicide runoff during normal nursery operation, if herbicides accumulate in containment ponds at nurseries, and how herbicide runoff could be reduced. A 2-year study at commercial nurseries found that herbicide concentrations were higher in containment ponds soon after herbicide application, when compared with months with less herbicide application; and herbicides did not accumulate over the 2-year period. Herbicide runoff was greatest immediately after application and up to 15% of the herbicide applied was lost in the first irrigation event after application when using more water soluble herbicides. Bed material and herbicide formulation were also important in determining the amount of herbicide lost. Total losses were highest from plastic- and fabric-covered beds when using granular formulations and highest from gravel beds when spray formulations were used. The combination of using cyclic irrigation and grass waterways resulted in a reduction of about 25% of isoxaben loss when compared with clay and gravel waterways with continuous irrigation. The effects of reduced herbicide treatments compared to standard spray schedules were evaluated on herbicide transport, weed development, and plant growth and health. Results indicated that plant marketability was not affected, and total herbicide runoff was significantly reduced. Based on these studies, several recommendations can be made to commercial container plant production nurseries, which should reduce herbicide runoff and thereby reduce the environmental concerns associated with nurseries.

EFFICACY OF TURF INSECTICIDES ON MIXED SPECIES OF NYMPHAL GRASSHOPPERS, 2002

This study was conducted to evaluate grasshopper control in turf-type fescue using several fertilizer/insecticide granular formulations. Plots were set up at the Plant Pathology Research Farm, Stillwater, OK on tall fescue turfgrass that was established on 04 Apr at a seeding rate of 10 lb/1,000 ft2, and mowed to 3 inch. Soil was a Norge loam. Treatments were applied on 03 Jun to 6.25 ft2 plots arranged in a RCB design with four replications. Granular treatments were applied by hand with a shaker and liquid treatments were applied with a hand-held pump sprayer calibrated to deliver 5 gal/1,000 ft2. Following application, field cages constructed of aluminum frames and nylon netting that measured 2.5 x 2.5 x 3 ft high were secured over the treated plots. Sixteen 2nd to 4th instar grasshopper nymphs were released in each cage. Efficacy was determined on 10 and 14 Jun by opening each cage and counting all live grasshoppers that remained. The data were analyzed using ANOVA, and means were separated with LSD. Percent control was estimated using Abbott's formula.

Monitoring of 15 Pesticides in Rainwater in Utsunomiya, Eastern Japan, 1999-2000<SUP>1</SUP>

Residues of 15 pesticides in rainwater were investigated monthly from July 1999 to July 2000 at five sampling sites in Utsunomiya, eastern Japan. Additionally, the residues for each precipitation were measured at one site. Among pesticides applied mostly as granular formulations to paddy fields, simetryn, pretilachlor, mefenacet and iprobenfos with small Henry's law constants were infrequently detected. In contrast, the herbicides thiobencarb and esprocarb with large Henry's law constants were frequently detected outside of the application periods, suggesting that the volatilization from water and soil surfaces had continued for a long time. The annual (July 1999-June 2000) deposited amount as an average value among the sampling sites was largest for fenitrothion at 546 μg/m 2 , followed by thiobencarb at 196 μg/m 2 , esprocarb at 109 μg/m 2 , and fenobucarb, diazinon and phthalide at about 40 μg/m 2 each. The relative standard deviations of the deposited amounts among the sampling sites were 30% or less. Fenitrothion, fenobucarb and phthalide were applied mostly as wettable powder, emulsifiable concentrate and dust formulations, allowing the pesticides to easily enter the atmosphere during the spraying or dusting process. The less variable distribution of these three pesticides is ascribable in part to the application of the above three formulations in large quantities. The annual deposited amounts of the other pesticides were about 20 μg/m 2 or less, with marked variation among the sampling sites.

The sound speed and attenuation in loose and consolidated granular formulations of high alumina cements

Clinkers of high alumina cements are separated into three granular formulations with particle sizes in the range 0.6–0.71 mm, 0.71–1.18 mm and greater than 1.18 mm. These are used to manufacture consolidated samples of porous concrete in an autoclave. The acoustic and microscopic properties of loose and consolidated porous samples of concrete are investigated using both experimental methods and mathematical modelling. Values of porosity, flow resistivity, tortuosity and parameters of the pore size distribution are determined and used to predict closely the sound speed, acoustic attenuation and normal incidence absorption coefficient of these materials. It is shown that high alumina cements do not require additional binders for consolidation and that the structural bonds in these cements are developed quickly between individual clinkers in the presence of water. The hydration product build-up during the consolidation process is insignificant which ensures good acoustic performance of the consolidated samples resulting from a sufficient proportion of the open pores. The value of porosity in the consolidated samples was found to be around 40%, which is close to that measured in some commercial acoustic absorbers. This work provides a foundation for the development of acoustically efficient and structurally robust materials, which can be integrated in environmentally sustainable concrete and masonry structures.

Enhanced Trehalose Accumulation and Desiccation Survival of Entomopathogenic Nematodes Through Cold Preacclimation

Limited storage stability is a major obstacle to further expansion of the use of entomopathogenic nematodes for pest control. Progress has been made that Steinernema carpocapsae can now be stored under partial anhydrobiosis for up to 6 months at 25°C and 10 months at 5°C in a water-dispersible granular (WG) formulation. However, other species have been more difficult to store in the WG formulation due to migration of nematodes out of the granules and sensitivity of some species to desiccation directly at cold temperatures. As acclimation to cold induces trehalose accumulation (a major cryo- and desiccation protectant) in many invertebrates, it was hypothesized that cold preacclimation of entomopathogenic nematodes will enhance their survival in the WG formulation at cold temperatures. This hypothesis was tested using a temperate species Steinernema feltiae , a subtropical species S. carpocapsae , and a tropical species Steinernema riobrave possessing different thermal niche breadths and reproduction temperature optima. Cold acclimation of infective juveniles increased trehalose accumulation in all three species and the amount of trehalose accumulated was both temperature and species dependent. Trehalose content reached at its peak after 6 days at 5°C in S. feltiae (82.28 w g/mg dry weight), after 10 days at 10°C in S. carpocapsae (94.16 w g/mg dry weight) and after 6 days at 15°C in S. riobrave (47.58 w g/mg dry weight). Cold preacclimation at 5°C for 2 days enhanced desiccation survival of S. feltiae in 25% glycerol (osmotic desiccation) at both 5 and 25° and of S. carpocapsae and S. riobrave only at 5°C. Non-cold acclimated S. carpocapsae and S. riobrave were extremely sensitive to desiccation directly at 5°C in 25% glycerol, resulting in over 98% mortality within 6 days, but S. feltiae was more sensitive to desiccation at 25°C than at 5°C. Cold preacclimation increased survival of all the three species in the WG formulation at both 5 and 25°C. The survival of S. riobrave at 5°C in the WG formulation was positively correlated with the length of preacclimation period at 5°C (R 2 = 0.99) and with the amount of trehalose accumulated during cold preacclimation (R 2 = 0.81). These results support the hypothesis that cold preacclimation enhances desiccation survival of entomopathogenic nematodes at cold temperatures and the increased survival correlates well with the increased trehalose accumulation. Results also demonstrate that cold preacclimation can be used as a tool to enhance survival of nematodes in the formulations with reduced water activity.

Formulation effects on isoxaben and trifluralin in runoff water from container plant nurseries

Abstract Sprayable and granular formulations of isoxaben and trifluralin were applied to container plant nursery beds to determine formulation effects on herbicide runoff and weed control. In 1998 herbicide application was followed by 0.8 cm of irrigation delivered in 60 min, and runoff water samples were collected on the day of application (DOA). The highest concentrations of isoxaben and trifluralin detected in runoff water were 0.50 and 0.15 μg ml−1, respectively. Total isoxaben in runoff water was greater from the granular than from the sprayable formulation, but no differences attributable to formulation were detected for trifluralin. In 1999 herbicide application was followed by irrigation applied in three pulse cycles of 30 min each (0.8 cm per cycle). Runoff water samples were collected daily through 2 d after herbicide application (DAA). The highest herbicide concentrations were found in the first runoff sample on the DOA. Isoxaben was detected at 1.6 μg ml−1 from both formulations, and triflural...

Granular phagostimulant nucleopolyhedrovirus formulations for control of Spodoptera frugiperda in maize

The efficacy of bioinsecticides that act by ingestion can be improved by the use of phagostimulant formulations that increase the consumption of the pathogen. A granule recipe comprising of pregelatinized flour, starch, ground maize cob, maize oil, and water was identified that was highly palatable to Spodoptera frugiperda larvae. To compare the performance of a multiple nucleopolyhedrovirus (SfMNPV) in aqueous spray and phagostimulant granules, multiple linear regression procedures were employed to analyze the results of seven independent field trials involving spray applications and eight independent field trials involving application of phagostimulant granules for control of S. frugiperda in maize. Prevalence of infection was positively correlated with the quantity of inoculum applied but negatively correlated with the interval between application and sampling of larvae for both granular and spray formulations. Virus-induced mortality was greater when inoculum was applied in granular than in spray formulation. A field experiment involving the application of 1:5 � 10 12 occlusion bodies (OBs)/ha in quantities of 6, 18, and 32 kg granules/ha indicated that the quantity of granules applied did not significantly affect viral mortality at any timepoint. Persistence of activity of viral inoculum applied in spray or granular formulations was significantly greater when applied in the granular formulation, with approximately 23% of the original activity remaining at 8 days postapplication compared to <1% in the spray-treated plants. We conclude that the efficacy of SfMNPV was improved by formulation; the granular formulation caused a higher prevalence of infection in S. frugiperda larvae and persisted longer on crop foliage compared to an aqueous spray application. The cost of the formulation ingredients alone was approximately US$0.50/kg. When combined with the virus, the cost of the basic bioinsecticide components would be about US$17/ha, although this estimate does not include additional costs involved in the commercialization of a potential bioinsecticide product. 2002 Elsevier Science (USA). All rights reserved.

Whorl and pollen‐shed stage application of Beauveria bassiana for suppression of adult western corn rootworm

AbstractThe corn rootworm complex is the most damaging insect pest of corn (Zea mays L.). This study was conducted to determine the efficacy of whorl and pollen‐shed stage applications of a granular formulation of Beauveria bassiana (Balsamo) Vuillemin for control of adult western corn rootworm (Diabrotica virgifera virgifera Le Conte). The effect of application time (whorl‐stage, pollen‐shed) and plant surface exposed (leaves and leaf collars; silks; leaves, leaf collars, and silks) on level of beetle fungal infection were investigated. In addition, the number of colony forming units of B. bassiana in the corn leaf collar area was quantified. In the three years (1998–2000) of the study, application of B. bassiana at whorl‐stage did not significantly increase beetle fungal infection. Beauveria bassiana applied to plants at pollen‐shed in 1998 resulted in a significant increase in beetle infection with 51% of beetles from treated plants infected and 6.0% from control plants. Similar applications at pollen‐shed in 1999 and 2000 resulted in very low infection levels. Beauveria bassiana application at pollen‐shed stage significantly increased the number of colony forming units per leaf collar during all years of the study. Beetle infection with B. bassiana did not differ consistently among plant surface to which beetles were exposed for either application. Increased fungal load in leaf collars was not correlated with increased levels of adult infection. Increased rates of B. bassiana and application when beetles are present on the plants are likely needed to significantly increase infection rates.

Integrated control of brown rot of sweet cherry fruit with a preharvest fungicide, a postharvest yeast, modified atmosphere packaging, and cold storage temperature

Abstract An integrated approach was studied for control of postharvest brown rot of sweet cherry fruit. System components included a preharvest application of propiconazole, a postharvest application of a wettable dispersible granular formulation of the yeast Cryptococcus infirmo-miniatus (CIM) Pfaff and Fell, storage in modified atmosphere, and storage at 2.8 °C for 20 days or −0.5 °C for 42 days. Preharvest propiconazole and postharvest CIM were similarly effective for control of brown rot. A significant propiconazole–CIM synergism was observed. Modified atmosphere significantly reduced brown rot compared to air-stored fruit. The storage temperature regime effect was inconsistent. This integrated decay control approach was effective and is especially relevant since postharvest fungicide options for cherry are limited.

Formulation of a Streptomyces Biocontrol Agent for the Suppression of Rhizoctonia Damping-off in Tomato Transplants

Abstract Formulations of a Streptomyces biological control agent for Rhizoctonia damping-off in tomato seedlings were developed for the first time from vegetative propagules obtained from actively growing, nonsporulating liquid cultures. Alginate beads, durum flour (starch) granules, and talcum powder formulation of this new actinomycetous antagonist ( Streptomyces sp. Di-944) isolated from the rhizosphere of field-grown tomato ( Lycopersicon esculentum ) suppressed damping-off caused by Rhizoctonia solani in tomato plug transplants (cv. Bonny Best) in a peat-based, soilless potting mix under greenhouse conditions. For formulations, vegetative biomass of Streptomyces sp. Di-944 from 3-day-old liquid fermentation in yeast extract–malt extract–glucose broth was lyophilized and pulverized to obtain fragments of viable vegetative filaments. The pulverized biomass had an initial viable count of 2 × 10 7 colony forming units/g and retained 100% viability for 2 weeks when stored at 4°C. Formulations stored at 4°C had a longer shelf life than those stored at 24°C based on viability at 2-week intervals over a 6-month storage period. In addition, dual culture tests showed declining efficacy for surviving Streptomyces propagules in formulations during this storage period. At 4°C, the powder and granular formulations were found to be the most stable and were shown to be 100% viable after 14 and 10 weeks of storage, respectively. However, at the end of 24 weeks, the number of viable propagules in the powder and granular formulations declined to 1.2 × 10 5 and 7 × 10 3 colony forming units/g, respectively. Alginate beads were the least stable in storage. Even at 4°C, 6.9 × 10 4 and 7.3 × 10 2 viable propagules/g formulation were detected at the end of 12 and 24 weeks, respectively. The talcum powder formulation delivered to tomato seeds as a seed-coating was the most effective biocontrol treatment. It suppressed damping-off in 10-day-old tomato transplants by almost 90% compared to 30 and 22% damping-off reduction when alginate beads or starch granules were delivered concomitantly with tomato seeds. Seed-coating with powder formulation of the biocontrol agent was as effective as drench application of the fungicide, oxine benzoate (No-Damp), in controlling Rhizoctonia damping-off and superior to the commercial biocontrol agent, Streptomyces griseoviridis (Mycostop), applied to tomato seeds as seed-coating.

Mosquito Control Evaluations of an Insect Growth Regulator, Pyriproxyfen against Culex pipiens pattens (Diptera, Culicidae) Larvae in Marsh Area, Korea

ABSTRACT Mosquito control evaluations of the granular formulation of 0.5% pyriproxyfen were undertaken in marshes and a pond in Busan during the period of July through September, 2001. In marsh condition where Culex pipiens pattens were predominantly breeding, the treatment of pyriproxyfen produced over an average of 95% mosquito larval reduction at a concentration of 0.05 mg/1 for the first 4 weeks in spite of heavy precipitation (total 274.4 mm) during the period. Reduction rates of 72.6% and 32.3% appeared in the 5th and 7th weeks probably due to heavy input of sewage and flood. However, the reduction rate increased again at the 8th week, showing a 94.5% reduction, probably because of the slow releasing of pyriproxyfen granular formulation. In the second treatment of pyriproxyfen, complete mortality was obtained at the 1st and 3rd weeks. Also, a satisfactory level of Cx. pipiens larval reduction of 96.6% was observed at the 4th week. In a pond assessment, the treatment of pyriproxyfen at a concentration of 0.05 mg/1 produced a complete reduction of Cx. pipiens pattens from the 1st week through the 4th week after treatment. In the second treatment, 100.0% reduction was obtained at the 1st and 2nd weeks in the same sites. The treatment resulted in 84.4% and 97.9% reduction of mosquitoes at the 3rd and 4th weeks, respectively.

Managing Termites in Maize with the Entomopathogenic Fungus Metarhizium anisopliae

Field experiments were conducted for two seasons to assess the efficacy of the entomopathogenic fungus Metarhizium anisopliae in the control of termites in maize. Application of the fungus at planting was found to significantly reduce maize lodging and increase grain yield in both seasons. However, data from treatment application at tasselling were not consistent. Our results suggest that a granular formulation of M. anisopliae might be a useful option for the management of termites in the maize agroecosystem.

Toxic Effects of Spinosad on Predatory Insects

Spinosad (Dow AgroSciences) is a mixture of tetracyclic-macrolide compounds produced by a soil actinomycete and has been classified as a bioinsecticide. Spinosad is highly active against Lepidoptera but is reported to be practically nontoxic to insect natural enemies. We assessed the impact of Spinosad in a granular maize-flour formulation on a selection of insect predators over periods of 2–14 days. In all cases, the quantities of Spinosad used were less than the maximum recommended rates given on the product label. Adults of Aleochara bilineata Gyllenhal (Coleoptera:Staphylinidae) suffered a high prevalence of mortality following consumption of 1000 or 2000 ppm Spinosad active ingredient (a.i.), but little mortality at 200 ppm. Larvae of Chrysoperla carnea (Stephens) (Neuroptera:Chrysopidae) did not consume the granular formulation and suffered little overall mortality. After 14 days of exposure, the earwig, Doru taeniatum (Dohrn) (Dermaptera:Forficulidae), suffered 48% mortality in the 1.2 ppm Spinosad treatment increasing to 98% in the 1200 ppm Spinosad treatment compared to 20% in controls. Earwigs suffered 86% mortality/intoxication 72 h after feeding on Spinosad-contaminated Spodoptera frugiperda J. E. Smith (Lepidoptera:Noctuidae) larvae. A field trial was performed to compare applications of commercial granular chlorpyrifos and Spinosad in maize-flour granules (200 and 2000 ppm a.i.; 4.8–48 g a.i./ha, respectively) or as an aqueous spray (160 ppm a.i.; 48 g a.i./ha) on earwigs held inside gauze bags. Mortality of earwigs on control plants was less than 15% at 2 days postapplication compared to 33% on plants treated with granular chlorpyrifos, 83% on plants sprayed with 160 ppm Spinosad, and 91–95% on plants treated with 200–2000 ppm Spinosad granules, respectively. Further mortality in the 24-h period postsampling ranged from <5% in control treatments, to 9% in the chlorpyrifos treatment, and to 55–65% in the Spinosad spray and granule treatments. We conclude that Spinosad cannot be considered to have an environmental safety profile similar to most established biological insecticides.

Formulation of a Nucleopolyhedrovirus with Boric Acid for Control of Spodoptera frugiperda (Lepidoptera: Noctuidae) in Maize

The degree of control of the fall armyworm, Spodo- ptera frugiperda, by a multiple nucleopolyhedrovi- rus (SfMNPV) appears to be limited by the quantity of inoculum consumed by the insect and the delivery of the virus to the insect feeding site. The formula- tion of the virus with phagostimulants and/or viral synergists, such as boric acid, may help overcome this problem. The present study aimed to determine the degree of potentiation of boric acid toward SfM- NPV in a granular phagostimulant formulation. In a laboratory bioassay the LC50 value for second-instar larvae was reduced from 114 virus occlusion bodies (OBs)/mm 2 of diet surface for virus alone to 51 OBs/ mm 2 of diet in the presence of 1% boric acid. The mean time to death of larvae exposed to virus mixed with 0.5 or 1% boric acid was not significantly differ- ent from that of larvae inoculated with virus alone. Increasing the concentration of boric acid at a single determined concentration of virus (80 OBs/mm 2 )r e- sulted in a significant increase in the prevalence of virus-induced mortality. The boric acid alone did not cause S. frugiperda mortality at the concentra- tions tested. A field trial performed with S. frugi- perda larvae held on plants within fine gauze bags indicated that application of maize flour granules containing virus 1 1% boric acid caused a significant increase in virus-induced mortality compared to ap- plication of granules containing virus alone. A ran- domized block experiment performed later also re- sulted in a higher prevalence of virus-induced mor- tality in S. frugiperda larvae exposed to virus mixed with 1% boric acid in samples collected at 5 days postapplication and reared in the laboratory until death or pupation, but not in samples made at 1 day and 3 days postapplication. Differences in the prev- alence of virus infection in insects collected at each time point may have been related to the consistency of the granular formulation, which turned into a paste and adhered to the surface of maize plants under con- ditions of heavy rainfall. Granules containing 1 and 4% boric acid were not toxic to the earwig, Doru taenia- tum, in the laboratory. The same concentrations of boric acid sprayed onto maize plants did not signifi- cantly reduce the abundance of natural enemies or other nontarget insects at any sample time point. Bo- ric acid offers an economical means of enhancing bac- ulovirus activity with little apparent risk to nontarget arthropods. © 2002 Elsevier Science

Integrated management strategies of bean root rot with Bacillus subtilis and Rhizobium in Minnesota

Dry bean root rot, caused by Fusarium solani f. sp. phaseoli, in association with Rhizoctonia solani and Fusarium oxysporum is an increasing problem in Minnesota. A standard seed treatment (SST) ( Captan 400+ Streptomycin+ Lorsban 50) has failed to effectively control the disease and resistant cultivars are unknown. The objectives of this study were to determine the effect of the biocontrol agents Bacillus subtilis strain GBO3 (Kodiak), MBI600 (Epic) and Trichoderma harzianum (T-22) on the incidence and severity of bean root rot; to compare conventional and granular formulations of B. subtilis, and to determine effectiveness of root rot control with co-inoculations of B. subtilis and Rhizobium. Greenhouse studies evaluated the effect of B. subtilis GBO3 and T. harzianum T-22 alone or in combination with Captan 400 and Vitavax 200 as biocontrol treatments in contrast to the SST. Seed application of both B. subtilis GBO3 and T. harzianum T-22 ( P>0.05) increased plant biomass and decreased disease severity (DS) under greenhouse conditions. Field experiments were conducted in 1997, 1998 and 1999 in naturally root rot infested fields at Staples and Verndale, MN. In 1997, seed treated with B. subtilis GBO3 reduced bean root rot and increased yield 31%, when compared to untreated plants. Bean seed inoculated with Rhizobium tropici UMR 1899 also increased yield 13% over the untreated control, though neither treatment eliminated disease. In 1998 in a grower’s field with favorable conditions for disease, three of the four treatments that included B. subtilis GBO3 outyielded the untreated control, and SST by 300–800 kg/ha, but in only one treatment were these results statistically significant ( P<0.05). In 1999, under severe disease pressure only co-inoculation with B. subtilis MBI600 (Epic) and R. tropici significantly reduced DS and enhanced yield relative to the control and SST treatments. Application of B. subtilis with Rhizobium is a promising approach for the improvement of bean root rot control.

Assessment of Plant Pathogenicity of Endophytic Beauveria bassiana in Bt Transgenic and Non‐Transgenic Corn

Field and greenhouse studies were conducted to determine the proclivity of Bacillus thuringiensis (Bt) (Berliner)‐transgenic corn (Zea mays L.) to form an endophytic relationship with Beauveria bassiana, and to evaluate the corn for possible plant pathological effects associated with this relationship. Beauveria bassiana (Balsamo) Vuillemin was applied as a granular formulation to two separate lines of corn, expressing Bt events MON802 and MON810, and their corresponding isolines. There were no significant differences in levels of endophytism between transgenic events or their near‐isolines. In greenhouse studies, B. bassiana was applied as a liquid seed treatment to Bt transgenic corn hybrids Pioneer 34R06 (event MON810) and Ciba Max 454 (event 176) and their near isolines at a rate of 2 × 1010 conidia per ml. There were no significant differences in seed germination or presence of root pathogens in transgenic or isoline seeds soaked in a B. bassiana suspension. The same lines of corn were used in field experiments with treatments of seeds soaked in a suspension of B. bassiana, a foliar application of a granular formulation of B. bassiana, and corresponding untreated checks. Plants were sampled throughout the growing season and evaluated for growth of individual plant components, including sheaths, leaves, stem, husk, ear, plant leaf‐to‐stem ratio and overall plant growth. There were no significant differences in overall plant growth between the B. bassiana treatments or in the growth of each plant component. The results of this study indicate that B. bassiana readily forms an endophytic relationship with transgenic and non‐transgenic corn and causes no plant pathology.

Control of malaria vectors with the insect growth regulator pyriproxyfen in a gem-mining area in Sri Lanka

The study was conducted in eight adjacent villages in central Sri Lanka where there are many shallow pits dug by gem miners that fill with water. These become breeding places of the main malarial vector Anopheles culicifacies, and of the second most important vector Anopheles subpictus, but not of Anopheles varuna, the third most important vector. With the help of local volunteers, data on the adult populations of these three species was collected by various standard methods, and data on the incidence of malaria cases was collected by two clinics set up for the project and through the existing hospitals. Prevalence of malaria infection in symptom-less people was investigated by mass blood surveys. On the basis of a year's pre-intervention data the villages were stratified into four with high levels of malaria transmission and four with lower transmission. Within each stratum two villages were randomly assigned for mosquito control by treating all the gem pits, as well as river bed pools, with a granular formulation of the insect growth regulator pyriproxyfen at a target dose of 0.01 mg a.i./litre. The intervention caused significant reductions in the adult populations of An. culicifacies and An. subpictus. Similarly, incidence of malaria was reduced in the intervention villages to about 24% (95% c.l. 20–29%) of that in the controls. Prevalence of parasitaemia also declined significantly. It is concluded that in this situation where, with active community participation, the breeding sites of the main vectors could be located; vector control by a highly active and persistent insect growth regulator can be a very effective means of malaria control.